Cylinder construction



CYLINDER CONSTRUCTION Filed Dc. 19, 1950 Patented Nov. 1, 1932 resist 1 OTTO NONNENBRUCH, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO I. PQMORRIS DE LA. VERGNE, INCORPORATED, A CORPORATION OF DELAWARE CYLINDER CONSTRUCTION Application filed'December 19, 1930, Serial No; 503,375.

diiiiculty encountered with an engine cylinder of uniform bore throughoutis that the portion of, the cylinder wall over which W thepiston rings travel is worn to a greater diameter than the remaining upper portion of the cylinder which is subject only to wear by the piston itself. The resultis that an annular shoulder isformed onthe cylinder 7 wall at the upper limit of travel of the topmost piston ring. Any attempt to remove the piston ,tl1I'OIlglI-thBftOP of the cylinder in order'to efi'e'ct any necessary repairs or inspection is obstructed or rendered diflicult by the piston rings engaging the annular.

' shoulder.

, To overcome the above difliculty it has been usual to counterbore' the upper portion of the cylinder starting at a'point very slightly below the upper limit of travel of the top piston ring.

This counterbore is sufficiently deep so that normally any wearing of the lower portion of the cylinder by the piston rings will not create a shoulder thus permitting relatively easy removal of the, piston. from the cylinder.- However the disadvantage offthis construction is that the counterbore exposes the to piston ring'tothe heat of combustion there y causing carbonization o of the lubricating oil in the ring groove. It is an object ofmy invention to provide an improved arrangement, whereby a uniformly bored cylinder and its piston may be. provided with only theus'ual small amount of clea-rance throughout thereby reducing vac-' cess of gases to the top ring and thus maintaining much lower'temperature of the top ring but yet avoiding the creation of a shoulder of such a character as will obstruct or hinder removal of the piston. It isthus seen that my improved arrangement contemplates obtaining the advantages both of a uniform cylinder and the counterboretype of cylinder without incurring the disadvantages of either. A further object'of the invention is to provide an extremely simple and yet effective arrangement whereby either a new or used cylinder may be arranged so as to accomplish the desired results. 1

A more specific object, is to provide an annular groovein the cylinder wall adjacent theuppermost limit of travel of thetop, piston ring and to have the upper surface of this annular groove or recess suitablyo shaped so that after the lower portionof the cylinder becomesworn said surface will then take on its function of acting asa cam or wedge to forcethe piston ring or rings ras.

dially inwardly if the piston is removedupwardly from the cylinder. f While the shape of thisgroove and its cam surface may be variedit is shown herein pref-. erably in the form of arstraight inclined surfacehaving a ratio of inclination of preferably three to one. This groove and the piston ring are so related in their dimensions that if a plain piston ringis used it will bridge across the groove when passing thereover during assembly thereby preventing the ring from expanding into the groove, while if the so-called double seal piston rings are used two cam surfaces are preferably provided in the form of a substantially V-shape annular groove to permit insertion of the piston into the cylinder without the possibility of any of the small parts of the split ring beingcaught by any shoulder of the groove. The dimensions of a double seal ring are such that it is preferable not to make the groove small enough to permit each part of the ring to bridge the groove with the resultthat each a part of the ring expands into the groove when passing the same but is gradually contracted by the lower inclined surface of the groove as the insertion of the piston .continues. It will be understood that if desired a relatively'narrow groove could be provided so as to permit each part of the ring to pass over the groove'during assembly without the necessity for the second, wedge or cam surface.' However, with any of the construe tions, during operation the upper or advancing edge of the top ring stops above the lower edge of the groove and preferably more nearly to the point of greatest depth thereof thereby avoiding the possibility of any shoul der being created. It is thus seen that as that portion of the cylinder starting at and ex.- tending below the groove is worn by the piston rings no abrupt shoulder is formed and thepiston is readilyv removable duejtothe: wedge action of the; upper inclined surfaceof what did constitute the groove.

Other objects and advantages-will be a131- parent to those skilled in the art from the following description of the accompanying drawing in which Fig. 1 represents a piston and: cylinder or cylinder liner provided with. my. improved arrangement for a double seal piston ring,

' Fig. 2 is a modified form of groove-adapted fora simple form.of seal ring,,and,

Fig. 8 shows a piston; being removed from, a worn cylinder with the piston ring engaging the inclined surface for effectingthe compressing action of the piston rings.

In the illustrated embodiment of my invention I have shown a cylinder 1 in which a piston2 is reciprocat'ed by any usual mechanismsuch for example as a rod 3'connected to a crankshaft. The cylinder as shown may be either a liner insertable within a cylinder block or itmay be the cylinder casting itself. In either case an annular groove 4 pref e'rably of' substantially V' shapev is formed in the cylinder wall at the point where theupper or'advancing'edge 5 of the top piston ring 6 stops in its uppermost limit of. travel. The piston ringshownin Fig; 1 is of the so-called double seal type which comprises'two duplicate parts 7 and 8 matched in any suitable manner so that they retain their same relative relation at all times. Inasmuch as any of thesevarious types of piston rings maybe used it'will suflice to point out that eacl i part of the ring is usually of. such a width that it -would expand into the recess 4 if" such a re cess was: made with a'desirable dimension. When any part of the piston ring expands intorthe groove during assembly itis-seen' that the lowerinclined surface 9'will contract the ring during downward'tmovement ofthe piston and hence will permit, the piston to be readily inserted in the cylinder.

In normal operation of the piston the upper part 7 of the double sealring never'completely passes the lower corner 10 of" the groove thus insuring that the piston ring will at all times be supported by the wall of the cylinder and wear the cylinder wall right up to the groove. Due to the radial pressure of the rings and combustion pressure thereon the cylinder gradually wears out to a: diameter such as is generally indicated by the dotted line 11 and as isshown in Fig; 3. The diameter of the greatest depth of the groove is preferably greater than that to which the cylinder is allowed to wear so that at no time will an obstructive shoulder be formed in the cylinder wall. Hence upon removal of the piston the top edge5 of. the ring will engage the inclined surface 4 and be pressed inwardly as. the piston is moved upwardly. The successive rings on the piston will likewise be pressed inwardly as they pass by the groove.

It is. thusseen that by' such an improved arrangement a cylinder of uniform diameter throughout may be employed thus resulting in having only the normal amount of small clearance between the-piston and cylinder at the portion thereof. abovethe groove 4-. This will; prevent undue exposure. of the PlStOIlrJZ to the heated gases. of combustion. thus re: ducing to. a minimurnthe. possihilityof carboni'zation of lubricant. in. the. ring} groove and at. the same, time there eliminated any possibility of an obstructing, shoulder being. formed'in the cylinder wall dueto wear. thereof by the piston rings. 1

The modification shown in Fig. 2 is best, adapted for a'single piecepiston ring, it being noted that the groove 4" has only one inclined surfacenamely its single ringcan entirely bridget'he same thus avoiding the necessity for a lowerinclined surface-such as 9'. Theoperation of this form is thesame as in the other form and the ad'- v'ant'ages are also "the same.

'VVhil'e I have specifically shown two forms which-the invention may assume it will of course be understood that modifications thereof maybe.- employedf without departing from the spirit ofithe invention as set forth in the appended claims.

I claim:

1. In combination, acylinder, a reciprocating piston therein, and a radially expansible sealingring carried by said piston, the wall of' said cylind'erhaving a cam-forming groove therein adjacent the point at which the ad vancmg edge of said pistonrin'g'stops in one limit of its travel, said" cylinder on each side ofsaid' groove being of smaller diameter than the groove.

21. In combination, a cylinder having a reciprocatingpi'ston therein, and. carried by said piston, in its wall adjacent the limit of travel ofsaid piston ring a groove provided with an inclined surface, whereby upon wear of the cylinder within the range ofjtravel ofthe piston; ring saidinclined surface may act to com press the ring during removal of the piston fromsaid-cylinder; v r

3. In combination, a cylinderof a substantiallyruniform diameter throughout its work: ing surface, a reciprocatingpiston. therein, a radially expansible piston ring; and means normallyprovided' asa portion ofsaid cylinupper surface; The width of this annular groove is such that a a piston ring; said cylinder having der whereby after wear of the cylinder withradially expansible piston ring, and means whereby after Wear of the cylinder within the range of travel of the piston ring said ring may be relatively easily compressed during removal of the piston from the cylinder, said means including a groove formed in the cylinder wall adjacent the limit of travel of the advancing edge of the piston ring.

5. In combination, acylinder of a substantially uniform diameter throughout its working surface, a reciprocating piston therein, a radially expansible piston ring, and means whereby after wear of the cylinder within the range of travel of the piston ring said ring may be relatively easily compressed during removal of the piston from the cylinder,

said means including an annular groove formed in the cylinder wall adjacentthe limit of movement of the advancing edge of the piston ring and the groove having an inclined surface in advance of said limit of travel.

6. In combination, a cylinder of a substantially uniform diameter throughout its working surface, a reciprocating piston therein, a radially expansible piston ring, and means whereby after wear of the cylinder within the range of travel of the piston ring said ring maybe relatively easily compressed during removal of the piston from the cylinder, said means including a groove formed in the cylinder wall adjacent the advancing edge of the piston ring, the point of greatest depth of said groove being intermediate the opposite edges thereof.

7. In combination, a-cylinder of a substantially uniform diameter throughout its work ing surface, a reciprocating piston therein, a radially expansible piston ring, and means including a cylinder wall cam-forming groove whereby after wear of the cylinder within the range of travel of the piston ring said ring may be relatively easily compressed during removal of the piston from the cylinder, said means also having provision where- 9. In combination, a cylinder of a substantially uniform diameter throughout its working surface, a reciprocating piston therein, a radially expansible piston ring, and means whereby after wear of the cylinder within the range of travel of the piston ring said ring may be relatively easily compressed during removal of the piston from the cylinder, said means including a groove formed in the cylinder wall adjacent the limit of travel of the piston ring and said groove having a width less than that of the piston ring whereby said ring is adapted to bridge said groove when the piston is inserted within the cylinder.

V OTTO NONNENBRUCH.

by the piston ring may substantially readily pass said groove in either direction thereof.

8. In combination, a cylinder of a substantially uniform diameter throughout its working surface a reciprocating piston therein, a radially expansible piston ring, and means whereby after wear of the cylinder within the range of travel of the piston ring said ring may be relatively easily compressed during removal of the piston from the cylin-s der, said means including a substantially V- shape groove formed in the cylinder wall adjacent the limit of travel of the advancing edge of said piston ring. 

